1. Technical Field
The present invention relates generally to a sheath for use in constraining a medical interventional device upon delivery to a body vessel in need of repair. More particularly, the invention relates to a splittable sheath for use in constraining an end of an expandable prosthesis upon insertion of the prosthesis into a damaged body vessel during an open surgical medical procedure.
2. Background Information
Trauma physicians frequently encounter patients having traumatic injury to a body vessel, such as lacerated vessels or even transected vessels, resulting from gunshots, knife wounds, motor vehicle accidents, explosions, etc. Significant damage to a body vessel may expose a patient to deleterious conditions such as the loss of a limb, loss of function of a limb, increased risk of stroke, impairment of neurological functions, and compartment syndrome, among others. Particularly severe cases of vascular injury and blood loss may even result in death. In such severe situations, the immediate goal is to obtain hemostasis while maintaining perfusion of adequate blood flow to critical organs, such as the brain, liver, kidneys, and heart.
Examples of treatment that are commonly performed by trauma physicians to treat body vessel injuries include the clamping of the vessel with a hemostat, the use of a balloon tamponade, the ligation of the damaged vessel at or near the site of injury, and/or the insertion of one or more temporary shunts. However, conventional surgical repair is generally difficult with actively bleeding, moribund patients. In many instances, there is not enough time to repair the body vessel adequately by re-approximating and suturing the body vessel. Thus, the trauma physician may simply insert a temporary shunt into the vessel. However, use of temporary shunts has been linked to the formation of clots. This may require returning the patient to the operating room for treatment and removal of the clots, often within about 36 to 48 hours of the original repair. Since such shunts are generally placed as a temporary measure to restore blood flow and stop excessive blood loss, the shunt is typically removed by a specialized vascular surgeon once the patient has stabilized (generally a few days later). After removal, the vascular surgeon will typically replace the shunt with a vascular graft, such as a fabric graft that is sewn into place. With respect to ligation, ligation of the damaged blood vessel may result in muscle necrosis, loss of muscle function, or a potential limb loss or death.
Due to the nature of the body vessel injury that may be encountered, the insertion of shunts or ligation of a blood vessel, for example, often requires that such treatments be performed within a very short period of time. Such treatments may occupy an undue amount of time and attention of the trauma physician at a time when other pressing issues regarding the patient's treatment require immediate attention. In addition, the level of particularized skill required to address a vascular trauma and stabilize the patient may exceed that possessed by the typical trauma physician.
Some open surgical techniques utilize sutures to affix damaged tissue portions to fittings that have been deployed with the vessel. Such techniques require the trauma physician to take sufficient time to tie the sutures properly. Even though in modern medicine sutures can be tied in relatively rapid fashion, any step in a repair process that occupies physician time in an emergency situation is potentially problematic. In addition, the use of sutures to affix the vessel to the fitting compresses the tissue of the vessel against the fitting. Compression of tissue may increase the risk of necrosis of the portion of the vessel tissue on the side of the suture remote from the blood supply. When present, necrosis of this portion of the vessel tissue may result in tissue separation at the point of the sutures. In this event, the connection between the vessel and the fitting may eventually become weakened and subject to failure. If the connection fails, the device may disengage from the vessel. Therefore, efforts continue to be made to develop suitable techniques that reduce the physician time required for such repair, so that this time can be spent on other potentially life-saving measures, and so that the blood flow may be more quickly restored and any resulting damage caused by lack of blood flow is minimized.
A device and a method for delivering a prosthesis for use in repair of a damaged body vessel during emergency open surgery are disclosed in my co-pending U.S. patent application Ser. No. 13/627,428, filed Sep. 26, 2012, titled “Delivery Device and System for Open Surgical Repair”. This document is incorporated by reference herein in its entirety. The incorporated-by-reference document discloses a device useful for delivering a prosthesis into a damaged body vessel, wherein each end of the prosthesis is constrained in a separate sheath upon insertion into the vessel. Once the sheaths and the prosthesis are positioned in the vessel, each sheath is split such that the respective ends of the prosthesis expand in the vessel. Barbs or other anchoring members at the ends of the prosthesis penetrate the vessel wall to anchor the prosthesis in the vessel. The intermediate length of the prosthesis bridges the damaged vessel portion to enable restoration of blood flow therethrough.
Splittable sheaths are well known in the medical arts. Examples of such sheaths are described, e.g., in U.S. Pat. No. 4,306,562 to Osborne and U.S. Pat. No. 4,581,025 to Timmermans, each of which is incorporated herein by reference in its entirety. Typically, prior art sheaths include one or more tab members that are pulled by the physician, often utilizing a needle holder or other clamping tool, to cause the sheath body to split in a longitudinal direction. With some prior art sheaths, as the tab and an accompanying sheath portion are withdrawn from the vessel, a portion of the sheath on the opposite side of the split line remains in the vessel. Following expansion of the prosthesis, this portion must also be removed from the vessel. Typically, this remaining sheath portion is captured by the physician utilizing a tool as described above, and thereafter removed from the vessel.
In order to facilitate withdrawal of the remaining sheath portion, a sheath in the incorporated-by-reference patent application cited above may utilize dual tabs. One tab is utilized for the initial splitting and removal of the sheath portion as described above. The other tab is associated with the remaining portion of the sheath. This tab provides a readily accessible target for the physician, and the sheath portion may be removed following expansion of the prosthesis by re-inserting the tool, capturing the tab, and withdrawing the tab and remaining sheath portion from the vessel. However, this dual-tab sheath does not eliminate a necessity to return to the vessel to remove a remaining portion of the sheath following the splitting and removal of an initial sheath portion.
It is desired to provide a modified sheath for use with an expandable prosthesis. It is further desired to provide a sheath for use with an expandable prosthesis during emergency open surgical procedures, in which the sheath is splittable and fully removable by the physician from the vessel and a prosthesis by pulling a single tab.